[PATCH V6 24/49] x86/entry: Use idtentry macro for entry_INT80_compat
From: Lai Jiangshan
Date: Fri Nov 26 2021 - 05:25:52 EST
From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
entry_INT80_compat is identical to idtentry macro except a special
handling for %rax in the prolog.
Add the prolog to idtentry and use idtentry for entry_INT80_compat.
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 18 ++++++
arch/x86/entry/entry_64_compat.S | 102 -------------------------------
arch/x86/include/asm/idtentry.h | 47 ++++++++++++++
arch/x86/include/asm/proto.h | 4 --
4 files changed, 65 insertions(+), 106 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 16b2215bdb23..dd0cb43627a3 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -371,6 +371,24 @@ SYM_CODE_START(\asmsym)
pushq $-1 /* ORIG_RAX: no syscall to restart */
.endif
+ .if \vector == IA32_SYSCALL_VECTOR
+ /*
+ * User tracing code (ptrace or signal handlers) might assume
+ * that the saved RAX contains a 32-bit number when we're
+ * invoking a 32-bit syscall. Just in case the high bits are
+ * nonzero, zero-extend the syscall number. (This could almost
+ * certainly be deleted with no ill effects.)
+ */
+ movl %eax, %eax
+
+ /*
+ * do_int80_syscall_32() expects regs->orig_ax to be user ax,
+ * and regs->ax to be $-ENOSYS.
+ */
+ movq %rax, (%rsp)
+ movq $-ENOSYS, %rax
+ .endif
+
.if \vector == X86_TRAP_BP
/*
* If coming from kernel space, create a 6-word gap to allow the
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 0051cf5c792d..a4fcea0cab14 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -311,105 +311,3 @@ sysret32_from_system_call:
swapgs
sysretl
SYM_CODE_END(entry_SYSCALL_compat)
-
-/*
- * 32-bit legacy system call entry.
- *
- * 32-bit x86 Linux system calls traditionally used the INT $0x80
- * instruction. INT $0x80 lands here.
- *
- * This entry point can be used by 32-bit and 64-bit programs to perform
- * 32-bit system calls. Instances of INT $0x80 can be found inline in
- * various programs and libraries. It is also used by the vDSO's
- * __kernel_vsyscall fallback for hardware that doesn't support a faster
- * entry method. Restarted 32-bit system calls also fall back to INT
- * $0x80 regardless of what instruction was originally used to do the
- * system call.
- *
- * This is considered a slow path. It is not used by most libc
- * implementations on modern hardware except during process startup.
- *
- * Arguments:
- * eax system call number
- * ebx arg1
- * ecx arg2
- * edx arg3
- * esi arg4
- * edi arg5
- * ebp arg6
- */
-SYM_CODE_START(entry_INT80_compat)
- UNWIND_HINT_EMPTY
- /*
- * Interrupts are off on entry.
- */
- ASM_CLAC /* Do this early to minimize exposure */
- SWAPGS
-
- /*
- * User tracing code (ptrace or signal handlers) might assume that
- * the saved RAX contains a 32-bit number when we're invoking a 32-bit
- * syscall. Just in case the high bits are nonzero, zero-extend
- * the syscall number. (This could almost certainly be deleted
- * with no ill effects.)
- */
- movl %eax, %eax
-
- /* switch to thread stack expects orig_ax and rdi to be pushed */
- pushq %rax /* pt_regs->orig_ax */
- pushq %rdi /* pt_regs->di */
-
- /* Need to switch before accessing the thread stack. */
- SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi
-
- /* In the Xen PV case we already run on the thread stack. */
- ALTERNATIVE "", "jmp .Lint80_keep_stack", X86_FEATURE_XENPV
-
- movq %rsp, %rdi
- movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
-
- pushq 6*8(%rdi) /* regs->ss */
- pushq 5*8(%rdi) /* regs->rsp */
- pushq 4*8(%rdi) /* regs->eflags */
- pushq 3*8(%rdi) /* regs->cs */
- pushq 2*8(%rdi) /* regs->ip */
- pushq 1*8(%rdi) /* regs->orig_ax */
- pushq (%rdi) /* pt_regs->di */
-.Lint80_keep_stack:
-
- pushq %rsi /* pt_regs->si */
- xorl %esi, %esi /* nospec si */
- pushq %rdx /* pt_regs->dx */
- xorl %edx, %edx /* nospec dx */
- pushq %rcx /* pt_regs->cx */
- xorl %ecx, %ecx /* nospec cx */
- pushq $-ENOSYS /* pt_regs->ax */
- pushq %r8 /* pt_regs->r8 */
- xorl %r8d, %r8d /* nospec r8 */
- pushq %r9 /* pt_regs->r9 */
- xorl %r9d, %r9d /* nospec r9 */
- pushq %r10 /* pt_regs->r10*/
- xorl %r10d, %r10d /* nospec r10 */
- pushq %r11 /* pt_regs->r11 */
- xorl %r11d, %r11d /* nospec r11 */
- pushq %rbx /* pt_regs->rbx */
- xorl %ebx, %ebx /* nospec rbx */
- pushq %rbp /* pt_regs->rbp */
- xorl %ebp, %ebp /* nospec rbp */
- pushq %r12 /* pt_regs->r12 */
- xorl %r12d, %r12d /* nospec r12 */
- pushq %r13 /* pt_regs->r13 */
- xorl %r13d, %r13d /* nospec r13 */
- pushq %r14 /* pt_regs->r14 */
- xorl %r14d, %r14d /* nospec r14 */
- pushq %r15 /* pt_regs->r15 */
- xorl %r15d, %r15d /* nospec r15 */
-
- UNWIND_HINT_REGS
-
- cld
-
- movq %rsp, %rdi
- call do_int80_syscall_32
- jmp swapgs_restore_regs_and_return_to_usermode
-SYM_CODE_END(entry_INT80_compat)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 6779def97591..49fabc3e3f0d 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -207,6 +207,20 @@ __visible noinstr void func(struct pt_regs *regs, \
\
static noinline void __##func(struct pt_regs *regs, u32 vector)
+/**
+ * DECLARE_IDTENTRY_IA32_EMULATION - Declare functions for int80
+ * @vector: Vector number (ignored for C)
+ * @asm_func: Function name of the entry point
+ * @cfunc: The C handler called from the ASM entry point (ignored for C)
+ *
+ * Declares two functions:
+ * - The ASM entry point: asm_func
+ * - The XEN PV trap entry point: xen_##asm_func (maybe unused)
+ */
+#define DECLARE_IDTENTRY_IA32_EMULATION(vector, asm_func, cfunc) \
+ asmlinkage void asm_func(void); \
+ asmlinkage void xen_##asm_func(void)
+
/**
* DECLARE_IDTENTRY_SYSVEC - Declare functions for system vector entry points
* @vector: Vector number (ignored for C)
@@ -433,6 +447,35 @@ __visible noinstr void func(struct pt_regs *regs, \
#define DECLARE_IDTENTRY_ERRORCODE(vector, func) \
idtentry vector asm_##func func has_error_code=1
+/*
+ * 32-bit legacy system call entry.
+ *
+ * 32-bit x86 Linux system calls traditionally used the INT $0x80
+ * instruction. INT $0x80 lands here.
+ *
+ * This entry point can be used by 32-bit and 64-bit programs to perform
+ * 32-bit system calls. Instances of INT $0x80 can be found inline in
+ * various programs and libraries. It is also used by the vDSO's
+ * __kernel_vsyscall fallback for hardware that doesn't support a faster
+ * entry method. Restarted 32-bit system calls also fall back to INT
+ * $0x80 regardless of what instruction was originally used to do the
+ * system call.
+ *
+ * This is considered a slow path. It is not used by most libc
+ * implementations on modern hardware except during process startup.
+ *
+ * Arguments:
+ * eax system call number
+ * ebx arg1
+ * ecx arg2
+ * edx arg3
+ * esi arg4
+ * edi arg5
+ * ebp arg6
+ */
+#define DECLARE_IDTENTRY_IA32_EMULATION(vector, asm_func, cfunc) \
+ idtentry vector asm_func cfunc has_error_code=0
+
/* Special case for 32bit IRET 'trap'. Do not emit ASM code */
#define DECLARE_IDTENTRY_SW(vector, func)
@@ -634,6 +677,10 @@ DECLARE_IDTENTRY_IRQ(X86_TRAP_OTHER, common_interrupt);
DECLARE_IDTENTRY_IRQ(X86_TRAP_OTHER, spurious_interrupt);
#endif
+#ifdef CONFIG_IA32_EMULATION
+DECLARE_IDTENTRY_IA32_EMULATION(IA32_SYSCALL_VECTOR, entry_INT80_compat, do_int80_syscall_32);
+#endif
+
/* System vector entry points */
#ifdef CONFIG_X86_LOCAL_APIC
DECLARE_IDTENTRY_SYSVEC(ERROR_APIC_VECTOR, sysvec_error_interrupt);
diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h
index 33ae276c8b34..597c767091cb 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -29,10 +29,6 @@ void entry_SYSENTER_compat(void);
void __end_entry_SYSENTER_compat(void);
void entry_SYSCALL_compat(void);
void entry_SYSCALL_compat_safe_stack(void);
-void entry_INT80_compat(void);
-#ifdef CONFIG_XEN_PV
-void xen_entry_INT80_compat(void);
-#endif
#endif
void x86_configure_nx(void);
--
2.19.1.6.gb485710b